作者:José Barluenga、Carlos del Pozo、Bernardo Olano
DOI:10.1055/s-1996-4160
日期:1996.1
Several reactions related to the ambident nucleophilicity of N-unsubstituted azadienes 1 are described. Thus, reaction of 1 with alkylating agents and iodobispyridinium tetrafluoroborate (IPy2BF4) leads to the C-substituted azadienes 3 and 5 respectively. Azadienes 1 and 3 are converted to the carbonyl derivatives 2 and 4 by mild hydrolysis. On the other hand, azadienes 1, 3 and 5 react through the nitrogen atoms with several carbonyl centered electrophiles to give nitrogen heterocycles such as pyrimidines 6 and 9 and dihydropyrimidines 11. All those processes are totally regioselective, azadienes 1 and 3 showing a lower nucleophilicity at nitrogen than N-substituted azadienes.
本文描述了与N-未取代氮杂二烯1的弱亲核性相关的几种反应。因此,1与烷基化剂和碘代双吡啶四氟硼酸盐(IPy2BF4)的反应分别产生了C-取代氮杂二烯3和5。氮杂二烯1和3通过温和的水解转化为羰基衍生物2和4。另一方面,氮杂二烯1、3和5通过氮原子与几种以羰基为中心的亲电体反应,生成氮杂环,如嘧啶6和9以及二氢嘧啶11。所有这些过程都是完全选择性的,氮杂二烯1和3在氮原子上表现出比N-取代氮杂二烯更低的亲核性。